Weight-graduated wire cable



July 31, 1951 R. STANTON 2,562,340

WEIGHTGRADUATED WIRE CABLE Filed June 17, 1950 2 Sheets-Sheet 1'3nnentor ZenL Sfanzon 2 Sheets-Sheet 2 INVENTOR.

July 31, 1951 R. STANTON WEIGHT-GRADUATED WIRE CABLE fioberil. Stanton aI .6 2 w a a p 4 au 6 0 l fi .1. g 2

Filed June 17, 1950 Patented July 31 1 951 IG T GK DU EDIWIHEQA ERobert-Ii. Stanton, Muncy, Rm, assignon=to..lnnes:- 8n Laughlin. Steel:Gorporatinm. Pittsburgh; ,Pa., amnporatim of rlienns van a nrli at muneSerial N; .68510 5 Claims. (01. 5 7.1145.)

This invention relates to wire; rope -or cable, and-isparticularly-concerned with cable adapted fjor well drilling bythe cabletoolmethod and similar uses.

As generally practiced, the cable tool method of drilling wellssuchvasoil and gas wells comprises the lifting and-dropping by a rope orcable and appropriatehoist-ingmeans of a relatively heavy drillgbit uponthe formation to be drilled. This method; of drilling-is'well adapted torelatively shallow. holes. and. requires simple. apparatus which canbeeasily transported over the frequently diflicult terrain; in which.drilling proceeds. Itsis limited to relativelyshallow holes, however,because of theweight' of; the cable itself which must be payed out, toreach great depths.- The upper; portion of thecable must, of coursesupport not only the weight of the tools but also the weightof'th'ecable in the hole, and even though wire cablesof high tensile strengthare. commonly; employed. the. deptlnof. a, hole which can beeconomically drillediinthisway is limited. If stronger,v andthereforeheavier, cablesare. used topermit drillingto greater-depths,the weight ofthe cable to be transportedandthe sizeand weight. of thehoisting apparatus. must be corresponding-1y. increased, which. in,turn. increases thedifficul-ty of .transportin the field. In practiceit. isgenerally consideredlthat theeco: nomical limit of cabletooldrilling isabout 6 ,000 feet if an adequate safetyfactor of cablestrength is tobe maintained.

The. lower endofthe cable in.the hole carries only the weight of thedrilling. tools, and the weight. carriedby. any successive sectionofcable increases gradually towardthe topof the hole. Conventional.cables. therefore provide anv unnecessarily large. factor, of safety atthe.bottom ofthe hole,..and. represent excess weight at. this pointwhichmustbe borne by, the upper. portion of.- the cable.

In.thev past, attempts have beenpmade; to in-. crease theeconomic-ultimate:depthof cable tool drilling by providing a, drillingcable tapering frpma relatively smalldiameter at the bottom end to a.larger diameter'at. the upper. end, and for a given total weight thesecablesdo permit the suspension. of. a. drillbit. andgreater length of.cable at a given factor. of safety thanispossible. with conventionalcable. However, tapered cables are difficult to make. Eurthermore, theyhave not enjoyed muchpracticalsuccess in cable tooldrilling because theydonot .allovvv the cable tooldriller, or tool. pusher as he is. commonlytermedto-judgethe progress of drilling, byhis usual: method. Toolushers, quite; generally gauge the progress of their drilling byWhatthey 22 call thefeel of the'rope-; that is; the vibrationtransmitted from the tools to the taut= cable at the top of the hole.Ithas beemfoundin+practice that a tapered cabl'e alters the characterofthis-transmitted vibration to-suchanextent that; itcannot be used asaguide by thetool pusher in the same manner-= as vibrations set up in ascable" of uniform diameter. Drilling with a-taperedcable, therefore,tends to-- besl'o wen than conventional drilling: and more prone te-kinking: or-breaking of the cable; sticking: oftools in -thei hole;- ordamage to-= these tools:

It is therefore an object of" my invention-to provide a cableforcabl'etool drilling-which is offuniform diameter throughout its length but-hasa unit weight and tensile strength which in.-" creases from the bottom"tothetop. It is another=object-of my -invention to provide such a; cablewhich has a-- more uniform safety factor: throughout its-length. It isstill anothen object. of myinvention-to provide such aweightegradu'nated cable which transmits vibratory impulses ine substantially the samemanner as: conventionali drillihgcables:

invention comprises a wire cable or rope of' conventional layandconventional section having' individual wires which; although of'con-astant diamete1 oven the length of the cable, arenot homogeneous; Thesecomposite wiresw which ferm the" strands; which inturn: comprise thecable, are in generalcomposed of steel: atithe upper end -oflthecablebut of a metal-lighter than steel at the bottom of the cable. Therelative lengths: of steel and lighter metal inthe com. positewiresareadjusted sethat successive crossa sections along the: cableshow aratio of lighter. metal to steelwhich increases by graduated amountsfrom one end: to: the other. A cable made. accordingto my. invention.therefore. ex hibits. a. uniform diameter; but progressively, de;creasing. unit weight. andultimate tensilestrpngtli. from one end to theother.

Reference; is now made to the figures which illustratethe cross-sectionof. a strand ofsuch. a. able- Fi' ure l. i5 3. cross section through astrandof a cable; of myinvention illustrating acon-van.- tional'arrangement of;wires.,.

Figuresm, 2b; and 2carecross sections through a cable strand embodying.my invention taken through successive portions of" thflstrand; Thesuccessive portions of the strand illustrated in this figureare'tabulated in'llablel following;

The strand shown is from a.- -inch 6-strand cable-of- 25 wire perstrand.The center wire or core: surrounded b wires; 2a: hrpu h. fsixzsmaller.wiresa known-.1 si illerr wires mm: .31;

3 inclusive, are laid between successive pairs of wires 2a through 2 Theexterior of the strand is composed of 12 wires, 4a through 4m. The corewire I and the wires of roups 2 and 4 are shown as having the samediameter, but it is not essential to my invention that this be the case.A cable according to my invention could be made with all the 25 wiresshown in the figures of composite construction. At the upper end of thecable all wires would be steel; at the lower end all wires would bemetal lighter than steel. The junctions or transition points at whichthe composition of wire would be changed from steel to the lighter metalcould be staggered along the length of the cable to provide a graduallydiminishing unit weight from the top of the cable to the bottom. Forcable tool drilling, however, I find it desirable to provide a cablecomprising a number of wires which are steel from top to bottom, and, toobtain the desired graduation in unit weight of cable, a number ofcomposite wires.

The three grades of steel commonly used in wire rope for drilling cableare mild plow steel having an average ultimate tensile strength of206,000 pounds per square inch, plow steel having an average ultimatetensile strength of 230,000 pounds per square inch, and improved plowsteel having an average ultimate tensile strength of 264,000 pounds persquare inch. It will be understood that the steel wires in my cable maybe ofone, two or all of these grades of steel, or in fact of othergrades if they prove economical.

The metal lighter than steel which I prefer to use is aluminum, althoughmy invention is not limited to this metal in combination with steel, orin fact to any specific metals. The aluminumv generally used for Wirerope has an average tensile strength of about 70,000 pounds per squareinch, and is only a little over one-third as heavy as steel. It istherefore possible to obtain a maximum over-all graduation in cableweight from top to bottom of nearly 3 to 1, and a similar graduation incable tensile strength of between 3 and 4 to 1. Furthermore, aluminumand teel-may be used together in the same strand or cable withoutdamaging electrolytic corrosion taking place as, although aluminum isslightly anodic to steel, it quickly forms a protective coating andbehaves in a more or less neutral fashion.

One embodiment of my invention is a cable 7,000 feet long comprising 6identical strands of 25 wires, each of these trands being composed of .421) illustrates the 4500-5000 feet section and Figure 20 illustrates the5000-5500 feet section.

The strand length is measured from the end which would be at the bottomof the hole in drilling. It will be seen that a strand formed astabulated above has a proportion of steel to aluminum that increases insteps from one end to the other. Other arrangements of wires in thestrand are possible, and my invention embraces a cable constructed ofseveral strands, each of which may consist of a different arrangement ofsteel and aluminum wires. In every such case, however, the diameter ofthe cable remains uniform from 'top to bottom as do the diameters of thestrands and the individual wires composing each strand.

The mechanical properties of a cable comprising 6 identical strandsarranged as in Table I are listed below. The tool weight assumed incalculating the safety factor was 3,500 pounds for the first 3,000 feetof hole drilled, 2,500 pounds for the next 2,000 feet, and 2,200 poundsfor the last 2,000 feet. These weights correspond aluminum wires of thegrade above mentioned and steel wires of all three grades abovementioned, arranged as in the following table.

Table I Strand I iength Steel Wires Aluminum Wires Feet 02,500.. l 1; 2athrough 2]; 30.

th h

4a through 4m (Mild Plow St el e roug 4a through 4m (Plow Steel)awe-7,000-..

Plow Steel); 4a through 4m (Plow Steel).

As has been mentioned, Figure 2a illustrates the 4000-4500 feet sectiontabulated above, Figure 1 Rounded to nearest whole number.

Wire strands, according to my invention, may be convenientlymanufactured in either of two ways. The first method employs separatespools of steel and aluminum wire at the strander. stranding iscommenced with steel wires, for example, if the cable'is to be formedwith all wires of steel at one end, or with wires of steel and wires ofaluminum if it is desired to have some wires of the latter metalthroughout the cable. After the desired number of feet of strand of theinitial arrangement of wires is formed, the strander is stopped and thedesired steel wires are cut and joined to aluminum wires of the samediameter. The stranding machine is then started up and the strandingcontinued for a measured footage, and the machine again stopped andadditional steel wire is cut and joined to aluminum wire, and so on. Thesecond method of manufacture, and one that I prefer to employ, requiresthe composite wires used in each strand to be formed in advance of thestranding. The required length of steel wire is measured, cut, and thenjoined to the required length of aluminum wire to form each compositestrand, and these strands are reeled up on spools which are then loadedvinto the stranding machine. The stranding of these prefabricatedcomposite wires can then proceed without in terruption. It will beunderstood that the aluminum and steel wires may be joined by welding orother suitable means.

As cable formed according to my invention must be utilized so that thelight end is the loadcarrying end, it is necessary that the two ends ofthe cable be marked so that identification of the light and heavy endsrespectively may be made. 1

Although I prefer to use aluminum as the lighter weight metal in thecomposite wires of my cable, other light weight metals may be used, suchas magnesium, or light metal alloys such as the alloys of aluminum, zincand magnesium.

Although I have described and illustrated the present preferredembodiment of my invention, it will be understood that the invention isnot limited thereto but may be otherwise embodied or practiced withinthe scope of my claims.

I claim:

1. A cable composed of continuous wires, including a plurality ofcomposite wires formed of steel at one end and a metal lighter thansteel at the other, the junctions between steel and lighter metal in thecomposite wires being staggered over the length of the cable.

2. A cable composed of continuous composite wires formed of steel at oneend and a metal lighter than steel at the other, the junctions betweensteel and the lighter metal being staggered over the length of the cableto provide a progressive decrease in unit cable weight from one end tothe other.

3. A cable composed of continuous wires of substantially constantcross-section, including a plurality of composite wires formed of steelat one end and a metal lighter than steel at the other, the junctionsbetween steel and lighter metal in the composite wires being staggeredover the length of the cable to provide a progressive decrease in unitcable weight from one end to the other.

4. A cable composed of continuous wires, including a plurality ofcomposite wires formed of steel at one end and a metal lighter thansteel at the other, the junctions between steel and lighter metal in thecomposite wires being staggered over the length of the cable to providea cable of substantially uniform diameter but progressively decreasingunit weight from one end to the other.

5. A cable composed of continuous wires, including a plurality ofcomposite wires formed of steel at one end and aluminum at the other,the junctions between steel and aluminum in the composite wires beingstaggered over the length of the cable to provide a progressive decreasein unit cable weight from one end to the other.

ROBERT L. STANTON.

No references cited.

